What this story made clear was that the existing drug tests out there are unable to detect some new drug that caused these events. It wasn't bath salts or PCP or LSD, those would have been detected. And grass by itself would NOT have that effect. Until they find out what drug is being distributed and/or contaminating grass, these cases will keep popping up. They still have no idea why this is happening.

As far as anyone can tell, yes, it was just grass. Many people have horrible reactions to weed. Personally, I become extremely paranoid, go straight into an anxiety attack and have heart palpitations from the stuff. But have never had any problem with cocaine, opiates, acid, mushrooms, booze, mescalin, etc. It's well within the realm of likelihood that the cannibal simply had a horrible reaction to weed as many people do. You may want to believe there was some undetectable cannibalism causing additive in his weed, but all signs point to that substance being the weed itself in reaction to his own individual body and brain chemistry.